A Colombian drug baron was assassinated in his hospital bed in Madrid Thursday night by a professional hitman.

Leonidas Vargas Vargas, head of the Caqueta cartel, was gunned down as he recovered from treatment for a heart problem.

The assassin, using a pistol fitted with a silencer, fired four shots before making his escape.

In a murder which had all the hallmarks of a professional hit, an accomplice waited at the door while Vargas was shot.

Another patient, who was sharing the same room, witnessed the shooting but was not harmed.

The patient’s wife later said: “My husband saw one of them. He was masked with a hat and a scarf.”

The shooting, which police believe was a settling of scores between rival Colombian drug gangs, happened just after 8 p.m. on Thursday.

Vargas, 59, whose underworld nickname was "El Viejo" (the Old Man), was being treated at a Madrid hospital while he awaited trial for drugs offenses.

A Spanish judge released Vargas on conditional bail which meant he had no police guard in the hospital.

He had been arrested in 2006 in Madrid and he was linked by Spanish prosecutors to the discovery of 1,100 pounds of cocaine hidden in a cargo of pineapples.

At the height of his influence, Vargas was known as The King of Caqueta and was said to control large cocaine laboratories in the Colombian jungle.

Click here to read more on this story from the Times of London.